The mechanism of transformation by avian oncoviruses will be explored by examining the expression of the src gene and env gene products in transformed chicken and mammalian cells. Antiserum to the pp60 transforming protein will be used to look at the intracellular distribution of the pp60src and possible association with cellular structures and molecules. These experiments will employ both biochemical and immunofluorescence techniques using cells infected by either wild type virus or virus temperature sensitive for transformation. In addition, a highly cross-reacting antiserum of the pp60src of various strains of avian sarcoma virus will be used to look for the protein product synthesized from the putative endogenous "sarc" sequences. Monospecific antisera will be prepared to the gp85 and gp37 viral envelope antigens. The expression of the type specific and two group specific antigenic determinants will be investigated in transformed mammalian cell by biochemical and immunological techniques. The possibilty that one or more of these antigenic determinants contributes to transplantation immunity will be explored.